Abstract
This paper is part two of a study on a CD 82 TMP chip refiner where relations between changes in the process conditions and changes in the properties of the produced pulp are investigated. Focus is on the ratio between tensile index and specific energy consumption when results from five tests are compared. Pulp properties were measured for composite pulp samples taken from the refiner blow line. Residence times and pulp consistencies were estimated by use of the extended entropy model. Clearly, an increase in specific energy does not necessarily implicate an increase in strength properties of the pulp produced. It is of high importance to have access to information about the refining zone conditions when searching for an optimal operation point in terms of the ratio between tensile index and specific energy. In these tests, this ratio had a maximum at about 55 % measured blow line consistency. Unfavourable operating conditions were identified at high pulp consistencies, especially after the FZ, where pulp consistencies well above 70 % were observed. The estimated residence time for each refining zone responded differently when applying changes in production rate, plate gaps and dilution water flow rates. In conclusion, the results associated with estimated pulp consistencies where easier to interpret compared with results for residence times, implying that additional tests are required for the latter variable. In addition to tensile index, pulp properties like freeness, Somerville shives and light scattering coefficient were included in the analysis.
Funding statement: This publication is part of the Energy Efficient Mechanical Pulping (e2mp) program at Mid Sweden University funded by the Knowledge Foundation, Stora Enso, SCA, Holmen, and Valmet. Special thanks to all who gave support to these trials and testing of the pulps.
Conflict of interest: The authors do not have any conflicts of interest to declare.
Appendix
Table 4
Test 2.
Composite Pulp Sample | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 |
Load, MW | 23.7 | 24.6 | 24.9 | 23.3 | 21.9 | 23.1 | 24.2 | 24.2 | 21.4 |
Gap FZ, mm | 1.35 | 1.20 | 1.05 | 1.21 | 1.37 | 1.35 | 1.36 | 1.35 | 1.36 |
Gap CD, mm | 0.78 | 0.79 | 0.78 | 0.77 | 0.77 | 0.79 | 0.78 | 0.75 | 0.78 |
Dil. water FZ, l/s | 3.42 | 3.43 | 3.43 | 3.43 | 3.43 | 3.36 | 3.26 | 3.17 | 3.43 |
Dil. water CD, l/s | 5.23 | 5.24 | 5.24 | 5.23 | 5.23 | 5.23 | 5.23 | 5.24 | 5.23 |
Prod., admt/h | 15.9 | 15.9 | 15.9 | 15.9 | 15.9 | 15.9 | 15.9 | 15.9 | 15.9 |
SE., kWh/admt | 1493 | 1552 | 1569 | 1473 | 1381 | 1457 | 1525 | 1527 | 1353 |
Calc. conc. FZ, % | 76.7 | 84.3 | 89.8 | 77.9 | 69.3 | 75.9 | 81.0 | 82.0 | 68.2 |
Calc. conc. CD, % | 60.0 | 64.1 | 65.4 | 58.9 | 53.7 | 58.6 | 64.0 | 65.3 | 52.3 |
Tot. res. time, s | 1.23 | 1.28 | 1.30 | 1.23 | 1.17 | 1.22 | 1.28 | 1.30 | 1.15 |
Res. time ratio FZ/CD | 1.03 | 0.98 | 0.97 | 1.04 | 1.11 | 1.05 | 1.00 | 0.99 | 1.13 |
Force FZ 3, N | 1.11 | 1.20 | 1.26 | 1.19 | 1.21 | 1.15 | 1.11 | 1.13 | 1.26 |
Pulp conc., % | 57.6 | 61.0 | 62.6 | 57.0 | 53.5 | 58.9 | 62.5 | 64.2 | 53.8 |
Freeness, ml CSF | 198 | 192 | 182 | 197 | 225 | 202 | 192 | 193 | 230 |
Fiber length (ww), mm | 2.11 | 1.96 | 1.92 | 2.15 | 2.29 | 2.20 | 2.03 | 2.01 | 2.31 |
CWT, μm | 7.8 | 8.0 | 7.8 | 7.9 | 7.8 | 8.0 | 7.9 | 7.9 | 8.0 |
Fibrillation, % | 5.43 | 5.64 | 5.62 | 5.39 | 5.56 | 5.82 | 6.06 | 5.67 | 5.62 |
Curl, % | 14.1 | 13.6 | 13.5 | 13.6 | 13.6 | 13.9 | 13.8 | 13.4 | 13.6 |
Somerville, % | 1.61 | 1.15 | 1.04 | 1.46 | 1.78 | 1.44 | 1.32 | 1.34 | 1.79 |
Density, | 329 | 352 | 362 | 343 | 330 | 343 | 348 | 358 | 326 |
Tensile index, Nm/g | 27.7 | 27.2 | 28.0 | 30.1 | 29.7 | 29.6 | 27.3 | 27.1 | 29.1 |
Elongation, % | 1.78 | 1.71 | 1.73 | 1.82 | 1.73 | 1.79 | 1.78 | 1.73 | 1.83 |
Tear index, | 6.37 | 5.72 | 5.86 | 6.72 | 7.21 | 6.88 | 5.95 | 6.11 | 7.27 |
Light scatt. coeff. | 45.3 | 47.7 | 48.1 | 45.9 | 43.2 | 45.5 | 47.0 | 47.8 | 43.5 |
Table 5
Test 3.
Composite Pulp Sample | 31 | 32 | 33 | 34 |
Load, MW | 22.4 | 22.1 | 22.1 | 21.9 |
Gap FZ, mm | 1.23 | 1.24 | 1.22 | 1.23 |
Gap CD, mm | 0.63 | 0.57 | 0.63 | 0.64 |
Dil. water FZ, l/s | 3.78 | 3.79 | 3.78 | 3.79 |
Dil. water CD, l/s | 5.12 | 5.11 | 5.12 | 5.06 |
Prod., admt/h | 15.0 | 15.0 | 15.0 | 15.0 |
SE., kWh/admt | 1496 | 1476 | 1470 | 1463 |
Calc. conc. FZ, % | 60.7 | 58.0 | 59.8 | 59.5 |
Calc. conc. CD, % | 50.6 | 49.6 | 49.4 | 49.5 |
Tot. res. time, s | 1.03 | 1.15 | 1.15 | 1.15 |
Res. time ratio FZ/CD | 1.13 | 0.99 | 0.99 | 0.99 |
Force FZ 3, N | 1.23 | 1.28 | 1.27 | 1.25 |
Pulp conc., % | 51.4 | 51.4 | 50.8 | 50.8 |
Freeness, ml CSF | 214 | 212 | 213 | 220 |
Fiber length (ww), mm | 2.22 | 2.21 | 2.28 | 2.20 |
CWT, μm | 7.9 | 7.9 | 7.8 | 7.9 |
Fibrillation, % | 5.48 | 5.31 | 5.72 | 5.72 |
Curl, % | 14.5 | 13.7 | 14.8 | 14.0 |
Somerville, % | 1.78 | 1.88 | 1.75 | 1.86 |
Density, | 316 | 328 | 337 | 340 |
Tensile index, Nm/g | 26.8 | 26.3 | 27.8 | 27.9 |
Elongation, % | 1.78 | 1.71 | 1.77 | 1.78 |
Tear index, | 6.42 | 6.36 | 6.82 | 6.79 |
Light scatt. coeff. | 44.0 | 44.2 | 43.8 | 43.9 |
Table 6
Test 4.
Composite Pulp Sample | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 |
Load, MW | 19.7 | 19.6 | 19.7 | 19.5 | 19.6 | 21.5 | 21.5 | 21.6 | 21.3 | 21.3 | 22.5 | 22.5 | 22.3 | 22.4 | 22.5 |
Gap FZ, mm | 1.48 | 1.48 | 1.48 | 1.49 | 1.48 | 1.48 | 1.47 | 1.47 | 1.48 | 1.48 | 1.49 | 1.48 | 1.48 | 1.48 | 1.48 |
Gap CD, mm | 1.14 | 1.14 | 1.13 | 1.13 | 1.14 | 1.15 | 1.15 | 1.15 | 1.15 | 1.14 | 1.11 | 1.12 | 1.14 | 1.14 | 1.13 |
Dil. water FZ, l/s | 3.39 | 3.39 | 3.39 | 3.39 | 3.40 | 3.41 | 3.40 | 3.40 | 3.39 | 3.39 | 3.38 | 3.41 | 3.40 | 3.43 | 3.38 |
Dil. water CD, l/s | 3.89 | 3.88 | 3.88 | 3.88 | 3.88 | 3.88 | 3.88 | 3.88 | 3.88 | 3.89 | 3.88 | 3.89 | 3.88 | 3.89 | 3.88 |
Prod., admt/h | 12.5 | 12.5 | 12.5 | 12.5 | 12.5 | 14.4 | 14.4 | 14.4 | 14.4 | 14.4 | 15.9 | 15.9 | 15.9 | 15.9 | 15.9 |
SE., kWh/admt | 1580 | 1566 | 1578 | 1564 | 1568 | 1490 | 1494 | 1497 | 1478 | 1482 | 1418 | 1415 | 1403 | 1410 | 1418 |
Calc. conc. FZ, % | 75.5 | 75.0 | 75.0 | 74.1 | 74.2 | 76.0 | 76.4 | 76.5 | 75.2 | 75.6 | 76.6 | 76.2 | 75.8 | 75.6 | 77.6 |
Calc. conc. CD, % | - | 58.6 | 58.6 | 57.6 | 57.7 | 64.5 | 64.9 | 65.2 | 63.9 | 64.2 | 65.9 | 65.4 | 65.0 | 65.3 | 66.1 |
Tot. res. time, s | 1.59 | 1.58 | 1.58 | 1.57 | 1.57 | 1.47 | 1.48 | 1.48 | 1.46 | 1.47 | 1.36 | 1.35 | 1.35 | 1.35 | 1.36 |
Res. time ratio FZ/CD | 0.85 | 0.85 | 0.85 | 0.86 | 0.86 | 0.80 | 0.80 | 0.80 | 0.81 | 0.81 | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 |
Force FZ 3, N | 0.56 | 0.55 | 0.56 | 0.58 | 0.58 | 0.79 | 0.78 | 0.80 | 0.78 | 0.79 | 0.99 | 1.02 | 1.00 | 0.99 | 0.99 |
Pulp conc., % | 56.7 | 63.2 | 60.3 | 58.9 | 58.8 | 67.7 | 68.5 | 70.4 | 64.0 | 65.8 | 70.8 | 73.2 | 70.9 | 69.5 | 75.8 |
Freeness, ml CSF | 183 | 198 | 190 | 191 | 194 | 235 | 235 | 260 | 226 | 253 | 303 | 327 | 295 | 280 | 307 |
Fiber length (ww), mm | 2.34 | 2.33 | 2.32 | 2.33 | 2.32 | 2.31 | 2.31 | 2.28 | 2.30 | 2.31 | 2.33 | 2.34 | 2.34 | 2.36 | 2.28 |
CWT, μm | 7.6 | 7.7 | 7.8 | 7.7 | 7.7 | 7.9 | 7.9 | 8.0 | 7.9 | 7.9 | 8.1 | 8.2 | 8.0 | 8.0 | 8.3 |
Fibrillation, % | 6.7 | 6.47 | 6.42 | 6.38 | 6.6 | 6.13 | 6.24 | 6.18 | 6.09 | 6.19 | 6.15 | 6.12 | 6.28 | 6.15 | 5.97 |
Curl, % | 15.3 | 15.1 | 15.1 | 14.9 | 15.4 | 14.4 | 14.6 | 14.5 | 14.6 | 14.6 | 14.6 | 14.6 | 15.0 | 14.8 | 14.2 |
Somerville, % | 0.88 | 0.92 | 0.85 | 0.78 | 0.95 | 1.26 | 1.27 | 1.22 | 1.32 | 1.28 | 1.40 | 1.54 | 1.43 | 1.39 | 1.34 |
Density, | 362 | 355 | 360 | 360 | 364 | 341 | 352 | 350 | 356 | 346 | 336 | 337 | 339 | 350 | 339 |
Tensile index, Nm/g | 34.4 | 31.6 | 33.1 | 32.9 | 32.9 | 28.1 | 28.6 | 28.0 | 30.5 | 28.4 | 25.5 | 24.5 | 27.2 | 28.1 | 24.9 |
Elongation, % | 1.92 | 1.83 | 1.86 | 1.91 | 1.88 | 1.75 | 1.66 | 1.67 | 1.71 | 1.69 | 1.53 | 1.56 | 1.63 | 1.68 | 1.56 |
Tear index, | 7.47 | 7.22 | 7.59 | 7.31 | 7.37 | 7.16 | 6.95 | 6.48 | 6.93 | 6.61 | 6.19 | 6.23 | 6.55 | 6.83 | 6.06 |
Light scatt. coeff. | 47.5 | 47.4 | 47.3 | 47.1 | 47.3 | 46.0 | 47.1 | 47.4 | 47.3 | 46.4 | 45.2 | 44.6 | 45.2 | 45.4 | 44.9 |
Table 7
Test 5.
Composite Pulp Sample | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 |
Load, MW | 21.9 | 22.3 | 22.1 | 22.1 | 22.6 | 18.4 | 18.1 | 18.5 | 18.9 | 18.7 | 20.0 | 19.0 | 18.8 | 17.6 | 17.4 |
Gap FZ, mm | 0.87 | 0.87 | 0.86 | 0.86 | 0.87 | 0.85 | 0.85 | 0.86 | 0.86 | 0.86 | 0.85 | 0.86 | 0.85 | 0.85 | 0.86 |
Gap CD, mm | 0.67 | 0.67 | 0.67 | 0.67 | 0.65 | 0.65 | 0.64 | 0.65 | 0.65 | 0.65 | 0.67 | 0.66 | 0.66 | 0.65 | 0.65 |
Dil. water FZ, l/s | 3.29 | 3.28 | 3.28 | 3.28 | 3.28 | 3.51 | 3.51 | 3.51 | 3.51 | 3.51 | 3.51 | 3.51 | 3.51 | 3.51 | 3.52 |
Dil. water CD, l/s | 4.69 | 4.70 | 4.70 | 4.69 | 4.70 | 4.69 | 4.69 | 4.69 | 4.69 | 4.69 | 4.45 | 4.44 | 4.45 | 4.44 | 4.44 |
Prod., admt/h | 14.2 | 14.2 | 14.2 | 14.2 | 14.2 | 14.3 | 14.3 | 14.3 | 14.3 | 14.3 | 14.2 | 14.2 | 14.2 | 14.2 | 14.2 |
SE., kWh/admt | 1540 | 1568 | 1555 | 1555 | 1588 | 1285 | 1264 | 1297 | 1321 | 1306 | 1407 | 1339 | 1322 | 1243 | 1223 |
Calc. conc. FZ, % | 61.2 | 62.5 | 62.1 | 62.2 | 62.5 | 53.4 | 52.9 | 53.6 | 54.3 | 53.9 | 56.4 | 54.6 | 54.2 | 52.4 | 51.9 |
Calc. conc. CD, % | 57.7 | 59.2 | 58.4 | 58.5 | 60.4 | 45.4 | 44.7 | 45.7 | 46.8 | 46.2 | 51.5 | 48.8 | 48.1 | 45.2 | 44.5 |
Tot. res. time, s | 1.16 | 1.17 | 1.17 | 1.17 | 1.18 | 1.04 | 1.03 | 1.04 | 1.05 | 1.05 | 1.10 | 1.07 | 1.06 | 1.04 | 1.03 |
Res. time ratio FZ/CD | 0.94 | 0.92 | 0.93 | 0.93 | 0.90 | 1.11 | 1.13 | 1.11 | 1.09 | 1.10 | 1.01 | 1.05 | 1.06 | 1.11 | 1.12 |
Force FZ 3, N | 1.56 | 1.64 | 1.62 | 1.63 | 1.68 | 1.28 | 1.27 | 1.30 | 1.32 | 1.31 | 1.42 | 1.29 | 1.30 | 1.25 | 1.26 |
Pulp conc., % | 59.0 | 61.2 | 59.6 | 60.7 | 61.4 | 45.0 | 43.7 | 45.5 | 48.0 | 48.6 | 49.0 | 49.7 | 48.7 | 44.3 | 44.4 |
Freeness, ml CSF | 190 | 194 | 194 | 203 | 205 | 262 | 270 | 259 | 252 | 253 | 214 | 235 | 244 | 286 | 295 |
Fiber length (ww), mm | 2.29 | 2.24 | 2.22 | 2.24 | 2.19 | 2.33 | 2.39 | 2.39 | 2.34 | 2.37 | 2.34 | 2.38 | 2.35 | 2.33 | 2.38 |
CWT, μm | 7.8 | 7.8 | 7.9 | 7.8 | 8.0 | 7.8 | 7.8 | 7.8 | 7.8 | 7.9 | 7.9 | 7.8 | 7.7 | 7.6 | 7.7 |
Fibrillation, % | 6.3 | 6.3 | 6.4 | 6.29 | 6.2 | 5.92 | 6.03 | 6.05 | 6.03 | 6.12 | 6.16 | 6.05 | 6.04 | 5.91 | 6.12 |
Curl, % | 14.7 | 14.5 | 14.5 | 14.9 | 14.4 | 13.7 | 14.0 | 13.6 | 14.0 | 13.9 | 14.2 | 13.9 | 14.1 | 13.8 | 13.9 |
Somerville, % | 0.86 | 0.76 | 0.75 | 0.80 | 0.64 | 1.75 | 2.00 | 1.66 | 1.75 | 1.72 | 1.32 | 1.42 | 1.75 | 2.24 | 2.28 |
Density, | 372 | 375 | 376 | 381 | 373 | 333 | 329 | 340 | 340 | 338 | 348 | 333 | 329 | 331 | 327 |
Tensile index, Nm/g | 34.2 | 33.8 | 33.9 | 33.5 | 32.1 | 27.9 | 26.8 | 28.5 | 29.1 | 28.8 | 31.2 | 29.0 | 27.2 | 26.0 | 25.8 |
Elongation, % | 1.80 | 1.83 | 1.81 | 1.91 | 1.82 | 1.76 | 1.71 | 1.76 | 1.81 | 1.76 | 1.85 | 1.78 | 1.78 | 1.68 | 1.75 |
Tear index, | 7.44 | 7.51 | 7.74 | 7.54 | 7.12 | 7.18 | 6.88 | 7.16 | 7.14 | 7.10 | 7.35 | 7.26 | 6.92 | 6.75 | 6.44 |
Light scatt. coeff. | 46.6 | 47.2 | 47.1 | 46.5 | 47.1 | 43.2 | 43.0 | 42.8 | 43.4 | 43.5 | 44.5 | 43.5 | 43.1 | 42.0 | 41.9 |
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